PSI - Issue 19

Mladen Lukić / Procedia Structural Integrity 19 (2019) 655–664

660

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Author name / Structural Integrity Procedia 00 (2019) 000–000

precision on the use of the existing fatigue (bridge) load model so that it fits to the reality. The Project Team will need to check the coherence of the rules in EN 1993-1-9 (2005) to new developments of loads for orthotropic decks. The key benefit will be the adaptation of the rules given in EN 1993-1-9 (2005) on the strength of orthotropic decks to the new developments on loadings in orthotropic decks so that the fatigue life previsions are in line with the observations. Its output would be harmonization of rules (on strength) in the new EN 1993-1-9 with modified rules in the new EN 1991-2. 2.2.6. Sub-task 6: Harmonization of fatigue rules with other parts of EN 1993 Fatigue issues are dealt with in several parts of EN 1993. Rules from other parts need to be harmonized and included in the new version of EN 1993-1-9 in order to minimize incoherencies and misunderstandings, e.g.:  Fatigue strength of threaded structural details in EN 1993-1-11 (2006) differs at the first view from that of similarly looking details in EN 1993-1-9 (2005);  Fatigue details have to be clarified with EN 1993-6 (2007) concerning the assumption of stresses;  Additional rules given in application parts such as EN 1993-2 (2006) or EN 1993-3-1 (2006) and EN 1993-3-2 (2006) and corresponding NAs might be adopted in the future EN 1993-1-9. The key benefit will be the coherence and harmonization of the standards giving a single place to look for the fatigue related rules: the new version of EN 1993-1-9. Its output would be clarification and harmonization of rules (on strength and / or verification) in the new EN 1993-1-9 with those form the new versions of EN 1993-1-11, EN 1993- 2, EN 1993-3 (today’s EN 1993-3-1 and EN 1993-3-2 will merge into one Eurocode part only), EN 1993-6. 2.2.7. Sub-task 7: Fatigue data analysis Detail categories given in EN 1993-1-9 (2005) correspond generally to detail categories given in IIW fatigue recommendations. Nevertheless, two different types of statistical analysis of fatigue data seem to have been used within the two documents, so that the shapes of the S-N curves are not the same and the variable amplitude verification formats differ too. One single method based on the new EN 1990 (there are no precisions in the actual EN 1990 (2002) on fatigue testing and the interpretation of such tests) needs to be defined in order to have an agreed approach for future evaluation of fatigue tests. Note: Working Group 6.3 within ECCS TC6 worked on this topic and made a proposal for the statistical analysis method for fatigue tests in line with the prescriptions of EN 1990 (2002). That method will be checked with the new version of EN 1990 and published within a background document on changes brought to the new EN 1993-1-9. The key benefit will be that such a proposal will be clearly established and in line with EN 1990. Its output would be the establishment of a unified method for fatigue data analysis for all Eurocodes. 2.2.8. Sub-task 8: Updating of detail categories (fatigue strength) tables The detail categories (fatigue strength of structural details), given in Tables 8.1 to 8.10 within EN 1993-1-9 (2005), were obtained on the basis of older test results. Furthermore, those results have never been officially published, although the document was prepared in… 1989! The abovementioned ECCS TC6 WG 6.3 checked and prepared a new edition of the document that will be published by the ECCS in the near future. In the meantime:  Many new tests have been carried out;  New details (e.g. new bolted connections, beams with shot nails, laser cuts, etc.) have been developed;  Investigations on existing riveted structures have been realized. On the basis of the information available in the frame of three items specified above, the fatigue strength tables (detail categories and associated fatigue strength curves) are expected to be enhanced. Some work has already been done by the Project Team. Fig. 2 and Fig. 3 show a comparison between the corresponding entrance in the existing fatigue strength table and in a proposal for the new strength table for the same type of constructional detail.